Money Precision API

Exact decimal money math. No floating-point cents — ever.

The Problem

0.1 + 0.2 = 0.30000000000000004. Splitting $100 three ways loses a cent. Tax extraction drifts. This API runs every calculation on BigInt fixed-point integers, so results are exact to the minor unit and parts always sum back to the total.

POST /v1/compute

add · subtract · multiply with 7 explicit rounding modes (incl. banker's rounding).

POST /v1/allocate

Split a total by weights with largest-remainder — no lost or phantom cents.

POST /v1/split

Even N-way split; remainder distributed deterministically.

POST /v1/tax

Add tax to net, or extract net+tax from a gross-inclusive amount.

Free

$0/mo
  • 200 requests/day
  • All endpoints
  • JSON + MCP

Pro

$9/mo
  • Unlimited requests
  • Batch up to 1000 ops
  • Priority support
  • MCP integration
curl -X POST https://api.lazy-mac.com/money-precision-api/v1/split \ -H 'content-type: application/json' \ -d '{"total":"100.00","ways":3}' # → {"parts":["33.34","33.33","33.33"],"exact":true}